Xcode debugger doesn't stop at breakpoint in watchOS app

Question

I've set a breakpoint in the applicationDidBecomeActive method in the WKExtensionDelegate class.

WatchExtensionDelegate.h

@interface WatchExtensionDelegate : NSObject<WKExtensionDelegate>
@end

WatchExtensionDelegate.m

@implementation WatchExtensionDelegate

- (void)applicationDidBecomeActive {
    [self refreshView]; // Breakpoint
    [self refreshData];
}

...

@end

Screenshot of breakpoint

---

The app works as intended. But the debugger doesn't stop. I use Xcode 9.4.1